Epidemiology of human rotavirus Types 1 and 2 as studied by enzyme-linked immunosorbent assay.

To determine the relative importance of two known serotypes of human rotavirus, we developed an enzyme-linked immunosorbent assay to differentiate serotype-specific rotavirus antigen and antibody. Using this technic, we studied the epidemiology of the two serotypes in acute gastroenteritis. Seventy-seven per cent of 414 rotavirus isolates were Type 2, and the remainder were Type 1. The serotype distribution was similar in specimens from children in Washington, D.C., and other parts of the world. Sero-epidemiologic studies revealed that most children living in the Washington, D.C., area acquired antibody to both types by the age of two years. An analysis of children who were reinfected indicated that sequential infections usually involved different serotypes and that illness caused by one serotype did not provide resistance to illness caused by the other serotype. These results suggest that, to be completely effective, a vaccine must provide resistance to both serotypes.

The uniqueness of human milk. Host resistance to infection.

PIP: Field observations are reported which support an assumption that human breast milk acts benefically through induced host resistance to infection. Though the mechanisms of this induced host resistance to infection are not clearly understood, this article suggests the following factors as important: specific antibodies to infectious agents, influences stimulating or inhibiting certain intestinal microorganisms, and nonspecific antimicrobial factors. Immunoglobulins are present in human milk, with IgA representing the most abundant; the role of complement and immunoglobulin in induction of resistance to infection is well-known. Since all immunoglobulins have antibody activity, it is conceivable that immunoglobulins provide the material for antibodies to various etiological agents; for example, serum IgA contains all types of antibodies; serum IgG has a wide variety of antibodies to viruses, rickettsiae, protozoa, H antigens of Salmonella, and bacterial antitoxins and incomplete Rh antibodies; and the IgM fraction contains antibodies to O antigens of Enterobacteriacae, Rh agglutinins, and syphilis reagins. Another aspect of human milk as an inducer of host resistance is the bifidus factor which promotes development of characteristic microflora; since the bifidobacteria metabolize a variety of sugars, producing large amounts of acetic and lactic acids and trace amounts of formic and succinic acids, these organisms affect pH and, hence, certain resistance factors. Other factors present in milk include lysozyme (muramidase), complement, interferon, and immune cells, all of which promote host resistance to infection.^ieng